Constitutional law is the study of foundational laws that govern the scope of powers and authority of various bodies in relation to the creation and execution of other laws by a government. A constitution binds a government or governments, limiting the contexts in which rules may be created, interpreted and force may be applied. Constitutions may reference various bodies, including organizations, associations, stateless peoples and nation-states.

Most commonly constitutional law is the law of these foundational laws, customs, and constitutional conventions in regard to nation-states. Not all nation-states have constitutions, though all such states have a jus commune, or law of the land, that may consist of a variety of imperative and consensual rules, that may be customary law, oral law and written law that apply in the various jurisdictions of such state. Of those nation-states that do have constitutions, not all are considered strictly written constitutions, as the laws that govern such issues may not be consolidated into one single constitution document or instrument. The constitutional law may be a matter of interpreting a variety of text which may also be informed by history, custom and unwritten constitutional conventions . Compare, for example, the written Constitution of the United States with British constitutional law, which arises from multiple sources including the Magna Carta, the common law, and other customary sources. In some countries the constitution is known as the Basic Law.

Constitutional laws may often be considered second order rulemaking or rules about making rules. Generally speaking constitutions may be of a federal type (see: federal state), in which several levels of government coexist with exclusive or shared areas of jurisdiction over lawmaking, application and enforcement. An example of this kind of constitution is that of the United States. In the European Union, though, there is heated debate about federalism, with some Europeans regarding a federalist Europe as a threat to national identity, while other Europeans would welcome a federal system. Constitutional laws may also be of a unitary type (see: unitary state) where the powers of government rest in one central administration and legislature, though in unitary constitutional states, there is often a delegation of power or authority to local or municipal authorities, however the central legislature retains the right to recall its authority at anytime.

Other types of constitutional law also exist, such as confederations, in which a group of nation-states each with its own sovereignty create a common body to deal with certain common issues in which limited powers are transferred to the confederation authority, common in custom unions . The central authority may be referred to in federal terms though on the clear understanding that it has no powers other than those specifically delegated to it by the participating states. Two examples of these types of constitutional system are the European Union and Switzerland. This was also the first form of government created by the thirteen colonies after the American Revolution in the Articles of Confederation. Some of the southern states of the USA attempted to return from federalism to confederalism in the nineteenth century but were prevented by federal military force in the American civil war.

Areas of Constitutional law

• US Constitutional Law

• Constitution of Ireland
• Australian Constitutional History.
• Spanish constitutional law
• Countries with Basic Law constitutions
• European Community law

See generally: List of legal topics